I don't have information on their entrance fee, but their phone number is 01223902088.
I am also looking for a train leaving on Tuesday from Broxbourne after 17:15 headed to Cambridge.
attraction-area attraction-type train-day train-departure train-destination train-leaveat
attraction-area attraction-type train-day train-departure train-destination train-leaveat
attraction-area attraction-name attraction-type train-day train-departure train-destination train-leaveat
attraction-area attraction-type train-day train-departure train-destination train-leaveat